Abstract
Close inspection of the channel maps which make up the high resolution M31 HI-data set (Brinks, this volume) resulted in finding numerous shell structures and bubble-like regions. To avoid any bias in the interpretation we shall call holes, in the course of this contribution, all those structures where we find a deficiency of neutral gas. Some of the holes can be identified directly in a total surface density map of M31, but due to blending of the various velocity components, e.g. the warp, holes tend to loose contrast. Therefore the best way to search for the holes is by inspection of the full resolution channel maps (δα x δδ x δV = 24″ x 36″ x 8.2 km s−1).
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